Sanding machine and sanding belt for use therewith



Oct. 20, 1970 M. DEL vEccHlo 3,534,503

SANDING MACHINE AND SANDING BELT FQR USE THEREWITH Filed Nov. 12. 1968 2 Sheets-Sheet l INVENTOR MICHAEL QDELVECCHIO Y FIG. 3 ma, g

ATTORNEYS Oct. 20, 1970 M. DEL VECCHIO 3,

SANDING MACHINE AND SANDING BELT FOR USE THEREWITH Filed Nov. 12, 1968 2 Sheets-Sheet 2 7 258 244 7 INVENTOR MICHAEL DELVECCHIO F G. 9 /6 296 L'ZZM@M ATTORNEYS United States Patent 3,534,508 SANDING MACHINE AND SANDING BELT FOR USE THEREWITH Michael Del Vecchio, 140 Regent Ave., Providence, RI. 02920 Filed Nov. 12, 1968, Ser. No. 774,934 Int. Cl. B24b 21/00, 23/06 US. Cl. 51-135 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The present invention relates to power sanding equipment, and is particularly applicable to portable sanding machines of the type which are commonly used for finishing automobile bodies. The prior known power sanding machines normally included a motor and a drive mechanism enclosed within a housing, the entire unit being small and light enough to be held in the operators hands. The drive mechanism rotated an endless belt that was applied to the work surface, the degree of advantage of such power sanders depending upon the linear drive speed of the sanding belt. Thus the greater the speed of the sanding belt the more efiicient and more effective the sanding operation.

Prior to the instant invention some efforts have been made to increase the rotational speeds of sanding machines, but high rotational speeds were dependent on stability and strength of the sanding belt. In particular, as the speed of the drive belt increased beyond a certain point, the sanding belt had a tendency to run laterally off the drive belt. As the drive speed further increased the sanding belt tended to deteriorate due to the stresses eX- erted thereon by centrifugal forces.

SUMMARY OF THE INVENTION The sanding machine of the present invention incorporates a sanding belt that is capable of relatively high operating speeds. In particular, the sanding belt cooperates with the sanding machine in such a manner that the sanding belt remains on the drive belt even at high operating speeds. In this connection, the sanding belt is constructed so as to resist shearing or parting that tends to occur from centrifugal forces encountered at high operating speeds.

In carrying out the concept of the invention the sanding machine embodied herein includes a drive belt having a pair of outwardly facing bearing surfaces separated by a longitudinally extending space. The sanding belt that is received on the drive belt is formed with a bead on the inner surface thereof, the bead being received in the space in the drive belt when the sanding belt is mounted thereon. The bead not only cooperates with the space to prevent lateral shifting of the sanding belt when the sanding machine is operated at high speeds but also increases the tensile strength of the sanding belt for resisting the stresses that occur at high operational speeds.

Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.

DESCRIPTION OF THE DRAWING In the drawing which illustrates the best mode presently contemplated for carrying out the present invention:

FIG. 1 is a front perspective view of a portable power sanding machine and a sanding belt for use therewith, as embodied in the present invention;

FIG. 2 is a rear perspective view of the sanding machine and sanding belt illustrated in FIG. 1 with one of the covers which form the housing of the machine removed to reveal the internal construction thereof;

FIG. 3 is a sectional view taken along the lines 3-3 in FIG. 1;

FIG. 4 is an elevational view, with parts shown in section, of one of the drive wheels and the drive belt and sanding belt as mounted thereon;

FIG. 5 is a perspective view, with parts broken away, showing the drive belt and sanding belt as employed in the sanding machine illustrated in FIGS. 1 through 4;

FIG. 6 is a sectional view showing the interconnection of the handle to the housing covers;

FIG. 7 is a perspective view, with one of the covers removed, illustrating an alternative embodiment of a sanding machine in accordance with this invention;

FIG. 8 is a sectional view taken through one of the drive wheels of the sanding machine illustrated in FIG. 7; and

FIG. 9 is a perspective view, with parts broken away, showing the drive belt and sanding belt employed with the sanding machine illustrated in FIGS. 7 and 8.

DESCRIPTION OF THE INVENTION The portable sanding machine as seen in FIGS. 1 through 6 is generally indicated at 10 and comprises a housing 12, a motor 14 and an endless belt of sandpaper 16 which is driven by a drive mechanism 18 located within the housing and powered by the motor. The housing 12 includes cover members 20 and 22, which cooperate to enclose the drive mechanism 18. A number of sockets 24, 26 and 28 project from the side wall of the cover member 20 into the interior of the housing 12 and abut against the inside surface of the side wall of the opposite cover member 22. Each of the sockets has a tapped opening 30 which is aligned with a screw aperture in the cover member 22, permitting conventional machine screws to be inserted through the apertures and threaded into the tapped openings for securing the cover member 22 to the cover member 20. As seen in FIG. 6, the tapped opening 30 of the socket 26 protrudes from the cover member 20 and receives a threaded shank 32 of a handle 34, the shank 32 being received in an aperture 36 formed in the cover member 22. The handle 34 not only aids in securing the cover members together, but defines a convenient gripping member for holding the sanding machine in the use thereof.

The drive mechanism 18 includes a drive wheel assembly generally indicated at 38 and a pair of idler wheel assemblies generally indicated at 40 and 42. A pair of endless drive belts 44 and 46 are received on the wheel assemblies 38, 40 and 42 and are rotatably driven therewith. The motor 14, which may be an air driven or electrically driven motor of conventional construction, is drivingly connected to the wheel assembly 38 through a shaft 48, the rotation of the wheel assembly 38 acting to drive the belts 44 and 46. The sandpaper belt 16, in turn, encircles the drive belts 44 and 46 and is rotated therewith, as will be further described hereinafter. The idler wheel assemblies 40 and 42 are supported upon respective shafts 50 and 52 to support the drive belts 44 and 46 and the sandpaper belt 16 at two locations spaced from the drive wheel 38. Conventional ball bearing assemblies 54, 56 and 58 that are mounted on the outside surface of the cover member 20 rotatably support the shafts 48, 50 and 52, respectively.

The cover members 20 and 22 are formed with a cut away portion 60 that extends from a point near the top of the idler wheel 42 around and below the idler wheel 42 and across the lower surface of the sanding machine to the idler wheel 40, so as to expose the sandpaper belt 16 for contact with the work surface. In order to support the sandpaper belt 16 in the region between the idler wheels 42 and 40, a backing plate 62 is provided that is secured to the interior surface of the side wall of cover member 20 by a bracket 64.

In assembling the sanding machine 10 and the sandpaper belt 16, it is necessary to slacken the tension on the drive belts 44 and 46 so that the sandpaper belt 16 can be mounted thereover. After the sandpaper belt is applied to the drive belts 44 and 46 they must then be retensioned in order for the machine 10 to operate properly. Accordingly, the assembly of the motor 14, ball bearing 54, shaft 48 and drive wheel assembly 38 is movable relative to the idler wheel 40 and 42 assemblies to adjust the tension of the drive belts 44 and 46. As shown in FIG. 3, a slot 66 is formed in the cover member 20, through which the shaft 48 extends, the slot 66 being large enough to permit rotation of the shaft 48 therein. The movable assembly 14, 54, 48, 38 is mounted upon a slide generally indicated at 68 which is reciprocable within a guide bracket 70 afiixed to the outer surface of the cover member 20 by means of screw fasteners 71. In order to adjust the slide 68 relative to the guide 70, a rod 72 is threaded into a tapped aperture 74 that is formed in a boss 76 on the slide member 68. The rod 72 may be manually rotated to advance or retract the slide 68 and for this purpose a toothed thumb wheel 78 is secured to the rod 72. The rear extension of the rod 72 is journaled within a boss 80 joined to the outer surface of the cover member 20, while the thumb wheel 78 is accommodated within a cutout 82 that is formed in the cover member 20.

Referring now to FIG. 5, the sanding belt 16 is shown being formed with a bead 90 that is received in a space 92 separating the drive belts 44 and 46. This construction provides a tongue and groove type of engagement between the sandpaper belt 16 and the drive belts 44 and 46, and prevents the sandpaper belt from shifting laterally with respect to the belts even when the motor 14 is run at high speeds.

In one form of the invention, the belt 16 includes an endless loop of tough cord 94 which is sandwiched between an outer layer of sheet material 96 and an inner layer of sheet material 98. The outer layer 96 is an endless strip of conventional flat sandpaper material having the usual rough exterior surface 100. In order to provide an uninterrupted area on the outer surface 100 so as not to interfere with the sanding operation, the cord 94 is received in a channel or groove 101 that is formed in the inner layer 98, the cord 94 and groove 101 defining the bead 90 and the upper surface of the cord being contiguous with the adjacent surfaces of the inner layer 98. The mating surfaces of the inner layer 98 and the outer layer 96 are glued, thereby enveloping the cord 96 therebetween. The initial lateral width of the inner layer 98 from edge to edge is somewhat greater than the corresponing lateral width of the outer layer 96. When they are glued together, however, the edges of the two layers are substantially congruent, and the extra width of the inner layer 98 is used to form a bight portion that surrounds the cord 94. The bead is located midway between the lateral edges of the sandpaper belt 16, and extends parallel thereto. As a result, the portions of the sandpaper belt 16 located on both sides of the bead 90 rest on outer bearing surfaces 102 and 104 of the drive belts 44 and 46, respectively, while the bead 90 projects inwardly into the space 92 that is formed between the drive belts and engages the, sides of the drive belts to prevent the sandpaper belt 16 from shifting laterally relative thereto during high speedoperation of the machine.

The parallel spaced relationship of the drive, .belts 44 and 46, which defines'the bead receiving space 92, is achieved by a novel construction of the wheel-assemblies 38, 40 and 42. Referring now to FIGS. 3 and 4, the drive wheel assembly 38. is illustrated and is representative of the construction of the three Wheel assemblies 38, 40 and 42. As shown, the wheel assembly 38 includes two distinct pulleys and 112, each of which is formed with an outer flange 114 and a groove 116 in.which the associated drive belt 46 or 44 is received. In order'to define the space 92 which accommodates the bead 90, the pulleys 110 and 112 are separated by an annular spacer disc-120 which is mounted on the shaft 48 and is positioned between the pulleys. The drive belts 44 and 46 ride in the grooves 116 between the spacer disc 120 and the flanges 114 of their respective pulleys 110 and.112. Consequently, the bearing surfaces 102 and 104 of the spaced belts 44 and 46 respectively support the portions of the sanding belt 16 located on both sides of its central bead 90, while the bead itself rests within the space 92 defined by the spacer 120. A similar structure of the idler wheel assemblies 40 and 42 is employed to define the beadreceiving space 92 at those locations.

Referring now to FIGS. 7 through 9, a modified form of drive belt and wheel assembly are illustrated and are employed in a sanding machine 210 that is generally similar to that shown in FIGS, 1 through 6 The sanding machine 210 includes a motor 214 that drives a wheel assembly 238 located within a housing 212. The housing is defined by cover members 220 and 222 formed witha cutout portion 260, a sanding belt 16 encircling the drive Wheel assembly 238 and idler wheel assemblies 240 and 242 and being exposed in the cutout portion 260. Sockets 224, 226 and 228 having tapped openings 230, backing plate 262, bracket 264 and screws 271 are all secured to the cover member 220 in the manner as illustrated for the like parts shown in FIGS. 1 through 6. As illustrated in FIG. 9, the sanding belt 16 is identical to that described above and includes the laminated outer and inner layers 96 and 98, the inner layer having a groove for, receiving the cord 94, wherein a bead 90 is defined.

The modified drive belt is illustrated in FIG. 9 at 244 and is formed in a one piece construction that defines outwardly facing bearing surfaces 302 and 304, the bearing surfaces 302, 304 supporting the margins of the sanding element 16 located on either side of the bead 90. The bearing surfaces 302 and 304 arealso separated by a groove 305 which extends below the surfaces 302 and 304 for receiving the bead 90 of the sanding belt 16 therein.

In order to accommodate the single drive belt 244,:the structure of the wheel assemblies 238, 240 -and.242 is somewhat different from their counterparts in the previous embodiment, and as shown in FIG. 8, the idler wheel assembly 240, which is representative of the other wheel assemblies 238 and 242 includes a pulley formed with opposed flanges 255 that define a'groove 256 for receiving the drive belt 244 therein. Formed-in'the body of the pulley 240 are opposed cavities 258 that receive ball bearing units 260 therein. The inner race of each ball bearing unit 260 is frictionally receivedon a shaft 262 that is conveniently fixed to the cover members 220 and 222. It is seen that when the drive belt 244 with the sanding belt 16 located thereon is mounted on the wheel assemblies 238, 240 and 242, the inwardly projecting bead 90 of the sanding belt is received in the groove 395 of the drive belt and the sanding belt is prevented from riding laterally off the drive belt 244 during a high speed sanding operation. It is also seen that the c011- struction of the wheel assemblies 238, 24% and 242 avoids the exterior bearing units as illustrated in FIG. 1.

In addition to the guiding and restraining function of the bead 99 as formed on the sanding belt 16, the bead 90 also provides additional hoop tensile strength to the sanding belt 16 and aids in preventing the sanding belt from flying apart under the influence of centrifugal forces which are exerted on the sanding belt in a high speed sanding operation.

While there is shown and described herein certain specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.

What is claimed is:

I. In a sanding machine, a housing, a motor mounted on said housing, a drive wheel drivingly connected to said motor, at least one idler wheel mounted in said housing, endless drive belt means engaging said drive wheel and idler wheel and being rotatably driven by said drive wheel, said drive belt means having outwardly facing surfaces separated by a longitudinally extending space, and an endless sanding belt received on the outwardly facing surfaces of said drive belt means and having a longitudinally extending bead formed on the inner surface thereof that is received in said space in said drive belt means, wherein said sanding belt is prevented from lateral shifting on said drive belt means during operation of said sanding machine.

2. In a sanding machine as set forth in claim 1, said drive wheel and idler wheel each including a pair of spaced grooves arranged in side-by-side relationship and separated by a partition, said drive belt means further including a pair of drive belts mounted side-by-side in said grooves, said partition defining said space therebetween.

3. In a sanding machine as set forth in claim 2, said drive Wheel and idler wheel each including a pair of separate pulleys mounted side-by-side on a common shaft, each of said pulleys being formed to define one of said side-by-side grooves.

4. In a sanding machine as set forth in claim 3, said partition being defined by a disc mounted on said common shaft between said side-by-side pulleys.

S. In a sanding machine as set forth in claim 1, said drive wheel and idler Wheel each including a single pulley formed to define a single groove therein, and said drive belt means including a unitary drive belt riding in said single groove, said space comprising a longitudinal recess on the outer surface of said unitary drive belt.

References Cited UNITED STATES PATENTS 1,587,124 6/1926 Lacy 51-174 1,837,250 12/1931 Born.

1,963,139 6/1934 Mattoon 15-51 2,898,712 8/1959 OConnor.

3,093,170 6/1963 Thayer.

OTHELL M. SIMPSON, Primary Examiner US. Cl. X.R. 5l--l70, 399 

